Publication Details

This chapter was originally published as: Bryant, EA, The magnitude and nature of 'noise' in world sea-level records, in R. Chowdhury and M. Sivakumar (eds.), Environmental Management Geo-Water and Engineering Aspects, Balkema, Rotterdam, 1993, 747-751. Copyright 1993 Balkema.


While average world sea-level is rising at a uniform rate of 1-1.5 mm yr-1, regional rates can vary by an order of magnitude. Over time scales of several years these rates can be 10-100 times greater because sea-level is affected at this scale by highly changeable meteorological and oceanographic variables. The inherent "noise" level in world sea-level records is 35 mm. Much of this is expressed as fluctuations on the order of 20-100 mm with a frequency of 3-5 years. This latter "noise" is highly coherent at tide gauges around the globe and appears unrelated to resonance or wave excitation in oceans. It is suggested that this variability reflects changes in the world hydrological budget linked to the Southern Oscillation. This latter phenomenon relates to the strength of trade winds in the tropical Pacific Ocean and can generate significant drying followed by flooding over continental landmasses.